Battery-powered implantable systems are now being used in a wide array of therapeutic and prosthetic applications such as cardiac pacemakers/defibrillators, drug pumps, and more recently, neurostimulators for Parkinsons, pain relief, middle-ear implant and cochlear implant. For most of these applications, the energy-density and life of currently-available batteries are insufficient to enable fully-implantable systems and the battery frequently remains external. In Phase II, Front Edge Technology (FET) proposes to continue the development, it commenced in Phase I, of an advanced rechargeable battery for fully implantable hearing prosthetics devices such as cochlear implants and middle-ear implants. Relative to the state- of-the-art rechargeable batteries, the proposed battery has three times the energy density, three times the battery life and half the recharge time. During Phase II, FET will produce high capacity batteries by stacking high energy density Phase I cells in a novel manner such that overall high energy density is maintained. Sufficient quantities of batteries will be produced to support extensive in-house testing and evaluation by both a major cochlear-implant manufacturer and an implantable battery manufacturer. Previously in Phase I, FET successfully demonstrated (i) ultra-high energy density single layer cells (800Wh/L) (ii) very long cycle life (>4000 cycles) and (iii) relatively fast recharge (6 minutes). Proposed Commercial Applications: Our initial battery will be designed for cochlear implants, which have current annual sales of approximately $ 425 million and expected to grow by approximately 20% annually. Upon completion of the cochlear demonstration battery, we will pursue the other implantable neuromodulation applications, which have current annual sales of $1.6 billion and expected to grow to $10 billion in 10 to 15 years. In addition to neuromodulation applications, our battery technology will be suitable for rechargeable batteries for hearing aids, currently estimated to be a $5 billion dollar industry. Thesaurus Terms: Implantable medical power source, thin-film battery, lithium battery, cochlear implant, neurostimulator power source, neuromodulation implant battery, hearing aid battery.